java - Inner interface class -

i had test inner class , return average value can't work properly.

i have class inner interface 2 methods , need test class nothing seems willing work.

i tried many ways still have no clue wrong?

can please have , try tell me i'm doing wrong or tell me need test class betterprogrammertask?

i add class inner interface , test class tries use it.

the test program is:

public class betterprogrammertask {      // please not change interface     public static interface node {         int getvalue();          list<node> getchildren();     }      // please not change interface      public static double getaverage(node root) {         /*           please implement method           return average of node values (node.getvalue()) in tree.          */         int suma = root.getvalue() + suma(root.getchildren());         int count = 1 + count(root.getchildren());         return suma / count;     }      private static int suma(list<node> nodes) {         if (nodes == null || nodes.isempty()) {             return 0;         }         int suma = 0;         (node n : nodes) {             suma += n.getvalue() + suma(n.getchildren());         }         return suma;     }      private static int count(list<node> nodes) {         if (nodes == null || nodes.isempty()) {             return 0;         }         int suma = 0;         (node n : nodes) {             suma += 1 + count(n.getchildren());         }         return suma;     } } 

the class test method is:

import main.java.org.example.betterprogrammertask.node;  public class testbetterprogrammertask implements betterprogrammertask.node {      public static void main(string[] args) {          int sum = 0;         double sumdouble = 0;         system.out.println("example iii");         // nodeimpl          //         // getaverage not accept node definition ?????         //         sumdouble = getaverage(node);           decimalformat 4 = new decimalformat("#0.00");         system.out.println("for process node average calculated  " + four.format(sumdouble));     }      //     // , average , getchildren not filled yet , still did not      // due errors in getaverage     //     @override     public int getvalue() {         // todo auto-generated method stub         return 0;     }      @override     public list<betterprogrammertask.node> getchildren() {         // todo auto-generated method stub         return null;     } } 

import static import methods getaverage. , create instance of node

package main.java.org.example;  import java.text.decimalformat; import java.util.list;  import static main.java.org.example.betterprogrammertask.getaverage;  public class testbetterprogrammertask implements betterprogrammertask.node {      public static void main(string[] args) {          int sum = 0;         double sumdouble = 0;         system.out.println("example iii");         // nodeimpl          betterprogrammertask.node node = new testbetterprogrammertask();         sumdouble = getaverage(node);  //rest unchanged 

nb: not recommend using main.java part of package.

nb2: use default methods if using java 8. , place getaverage method, it's implementation on node interface, not have import method statically , call member of node.